A French actor with roots in Tunisia, Adam Bessa, is garnering critical accolades as the protagonist in Jonathan Millet’s debut feature, “Ghost Trail.” Mr. Bessa cuts a brooding, often hard-to-parse figure playing a Syrian refugee tracking his way through Europe — as well he should, considering his character, Hamid, has undergone travails that don’t beggar the imagination so much as confirm one’s worst fears about the base potentialities of humankind. Is Hamid’s stoicism an innate trait or a survival mechanism? It’s hard to say.

The antagonist of Mr. Millet’s picture is — well, what is the true name of the man portrayed by Tawfeek Barhom? At the French university at which he’s studying he’s known as Hassan and, like Hamid, he is a member of the Syrian diaspora. Hassan is eager to distance himself from his countrymen. That’s the primary reason he left Germany: Too many Syrians in the mix. Strasbourg is a necessary respite from birds of a feather.

Hassan’s views on displaced Syrians are of a piece with his elliptical take on the regime of Bashar al-Assad. Upon sitting down with Hamid, Hassan dodges and feints in his conversation, being pointed in intonation but vague in particulars. Mr. Barhom gives a mesmerizing performance, inhabiting a man whose caginess is indistinguishable from his mendacity. Mr. Millet’s camera accentuates the close-shaven angularity of the actor’s features, making Mr. Barhom seem, at times, more bone than skin.

The crux of “Ghost Trail” is the divination of Hassan’s true identity. Could he be Harfaz, a former torturer at the notorious Sednaya prison, a facility colloquially known as the “human slaughterhouse?” Mr. Millet, who co-wrote the script with Florence Rochat, based “Ghost Trail” on the true story of Kais Al-Abdallah, a Syrian refugee once ensconced in Germany. The courts couldn’t muster enough evidence to try him for “suspicion of terrorist activities,” but the Criminal Courts in Paris had a boost from information provided by an underground organization dubbed the Yaqaza Cell.

How much truth can be gleaned from “Ghost Trail”? Having lived for some time at Aleppo, Mr. Millet kept in contact with friends and acquaintances, learning that his old neighborhood had been demolished by government forces: “I met a large number of Syrians and listened to their stories of war, imprisonment, and torture.” His research led him to secret cadres of Syrians whose mission is to track Mr. Assad’s henchmen and bring them to justice.

“Ghost Trail” is a cat-and-mouse spy thriller whose parameters glance on fact. Our hero, the sullen Hamid, is part of a secret society that communicates primarily through a combat video game. Names, if not locations, are kept secret, though Hamid does meet regularly with a woman we come to know as Nina (Julia Franz Richter), an operative who lost her Syrian husband to the vagaries of war. As Hamid winds his way through various internment camps searching for his nemesis, he meets the statuesque Yara (Hala Rajab), who is, at least initially, wary of this stranger’s inquiries. Best to be careful: Mr. Assad’s agents are everywhere.

Hamid’s pursuit of Hassan is deftly put into place by Mr. Millet, who favors a gradual build-up of narrative increments not only to generate suspense but as a means for yoking more intensive facets from his characters. Although “Ghost Trail” is very much a chase movie — that is, after all, implicit in the title — the final catch is less important than the transformation of the character doing the chasing. 

The director states that he is incapable of making a film absent some indication of hope. Whether he’s done so here can be decided by moviegoers eager for a night of sitting on the collective edge of their seats.